Robert oliver



Nn. 609,363. Patented Aug. I6, |898.

'constitutes my invention.

` n iran e Artnr ROBERT OLIVER, OF NEV YORK, N. Y.

SHIPS COMPASS.

SPECIFICATION forming part of Letters Patent No. 609,363, dated August16, 1898. Application led September 11, 11897". Serial No. 651,3;761 (Nomodel.)

To @ZZ whom it may concern;

Be it known that I, ROBERT OLIVER, a citi- `zen of the United States,residing at New York, (Brooklym) in the county of Kings and State of NewYork, have invented new and` and in which the arrangement of the magnetsis such that at one side of the equatorial line there shall be a uniformdistribution of northpolar force at equidistan-t points and that at theother side of saidline there shall be a like distribution of south-polarforce.

By my invention I provide a compass having great directive force,whichis more sensi-4 tive and steadier than those heretofore used, capable offar more perfect adjustment than has been possible with thosemanufactured prior to my invention, and which is not affected by theknown-eccentric action of the usual correcting-magnets to whichcompasses prior to my present invention are subject.

To enable those skilled in the art to which my said invention relates tofully understand and to make, construct, and use the same, I will nowproceed to explain said invention in detail, reference being had forthis purpose to the accompanying drawings, in Which- Figure l is a planview of a compass-card removed from the binnacle, bowl, ornotationchamber,'part of the card being broken away upon one side todisclose the arrangement of bar-magnets and horseshoe-magnets which Fig.2 is an edge elevation of the same.

Mariners compasses as heretofore constructed have been provided withstraight bar-magnets arranged at substantially uniform intervals beneaththe card or with U- shaped or horseshoe magnets secured to the card atsuitable intervals with their polepieces in or nearly in linewith theperiphery of the card. In one oi' these forms there was a space of aboutforty-five degrees of arc between the opposite poles of the magnetscarry.

Y which crossed the equatorial line nearest to ythe east and west sidesof the card which was entirely unoccupied and in which there was nopolarity. In the other'case this dead-space extended over ninety degreesof arc or therev about, having about forty-five degrees north Vand anequal space south of the equatorial line in which no polar force waspresent. In

`the latter case also, `as V,horseshoe-magnets were used each having twopole-pieces of `north and south polarity, respectively, the

one polarity negatives theother and the compass is impaired rather thanbenefited by the dead-weight of useless metal it must In my presentinvention I employthe compass-.card l, with a series of bar-magnets 2,

arranged in parallelism one with another and at substantially uniformintervals of separation. These magnets are of hardened steel, and beingonce saturated with magnetism they retain it, their ends being ofopposite polarity. Theycross the equatorial line or east and Westmeridian at right angles thereto; but as the endsof said line areclosely approached t'Wo unoccupied arcs or portions of the cardperiphery are left deprived of polar force, this being due to the factthat the reduction in length of the permanent bar-magnet rendered it soweak as to be of no value. The dead-space thus produced extended fromthe east-northeast point to east-southeast or thereabout and alsowest-northwest to westsouthwest or thereabout, as shown in Fig. l of thedrawings;

As thus far described, the construction is like that disclosed in myLetters Patent No. 478,017, dated June 28,1892.

My present invention is designed to overcome the faults heretoforeexisting, as above referred to, and to attain the positive advantageshereinbefore set forth. To these ends I attach to the card I two or moreU-shaped or permanent horse-shoe magnets 3, secured to and lying beneaththe bar-magnets 2, with their legs upon opposite sides of the equatorialline and possessing a polar force equal to that of the bar-magnets. Thusthose legswhich of said line.

IOO

attraction of the horseshoe-magnets is so arranged as to augment thepolarity of the barmagnets 2, instead of counteracting the same.Moreover, I utilize the entire periphery of the card, leaving nodead-spaces, and thereby gain the advantages heretofore specified byimpartinga greater directive force, increased sensitiveness andaccuracy, greater steadiness, and more perfect adjustment.

As shown, the horseshoe-magnets 3 are mounted upon and secured to thebar-magnets 2, to which `they may be soldered or attached in any othermanner preferred.

AS before stated, the improved construction herein set forth is notsubject to the known eccentric action of the correcting-magnets, whichis a distinct advantage over prior constructions.

In the Compasses in general use on board ship the card is the only realfixture, the compass-bowl and box and the binnacle and the ship itselfhaving partial rotation or movement with respect to the card, whichmaintains a fixed position under the polar influence of the earth. As iswell known, correcting-magnets are provided to compensate for localmagnetic attraction, and these correcting-magnets partake of thedescribed movement with respect to the compass-card. Thecorrecting-magnets are disposed in part with their poles pointing foreand aft the ship and in part pointing transversely thereof, and as theyrotate or move with relation to the compass-card constructed prior to mypresent invention they approach and recede from the needles or poles ofthe magnets of the compass, and this approaching and receding movementis what I have hereinbefore termed the eccentric action of thecorrecting-magnets. This action existed in the construction shown in myLetters Patent mentioned, but

was limited to that portion of the card twentyfive degreesnorth andsouth of the equatorial line. The increase or decrease of the distancebetween the poles of the correctingmagnets and the card-magnetsresulting in a progressive increase or decrease of the mutual attractiveforce constitutes a material disadvantage in the prior constructions,taking from the sensitiveness and accuracy, and is entirely overcome bymy present invention, in which the provision of the horseshoe-magnetsestablishes a uniform and equidistant polar force around the periphery,because the poles of the correcting-magnets are always equally distantfrom thev card needles or magnets.

Vhat I claim is- 1. In a mariners compass, a compass-card havingstraight permanent bar-magnets arranged thereon parallel to a north andsouth meridian, and permanent U shaped, or horseshoe magnets, arrangedwith their' legs on opposite sides of the equatorial line, substantiallyas described.

2. In a mariners compass, the combination with a compass-card ofstraight, permanent bar-magnets arranged at intervals in parallelismwith a north and south meridian, and one or more permanenthorseshoe-magnets attached to said bar-magnets and having the legs ofnorth polarity upon the same side of the equatorial line as the ends ofthe barmagnets having a like polarity, substantially as described.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

ROBERT OLIVER.

Witnesses:

EDWARD W. TAPP, HENRY MARTIN.

